1. Field of the Invention
The present invention pertains to fill-control devices for dishwashing machines and, more particularly, to floats which prevent over-filling of dishwashing machines.
2. Description of the Related Art
Dishwashing machines typically include a fill or inlet valve which is operable to admit water into an interior of a dishwasher tub. A timer is usually provided to open the fill or inlet valve for a predetermined time at the beginning of each wash cycle to thereby admit a volume of water necessary to clean the dishes housed within the tub. In order to safeguard against over-filling the tub due to variations in water pressure, floats have been employed which actuate switches or control means that turn off or close the fill or inlet valve when the water level within the dishwasher tub reaches or exceeds a predetermined level.
U.S. Pat. No. 5,018,550, the disclosure of which is expressly incorporated herein in its entirety, is exemplary of such fill control floats. The '550 float has a generally cylindrical body with an outwardly and downwardly extending skirt, and a centrally located float stem. The lower edges of the cylindrical body and skirt are co-planar. The stem projects downwardly from the cylindrical body through a stand pipe provided by the tub bottom, and actuates a control switch when water level within the tub reaches a predetermined level, thereby closing the inlet valve. Downward movement of the float is limited by engagement with the stand pipe in which the float stem is inserted and spaces the lower edges of the cylindrical body and skirt a distance away from the bottom of the tub, allowing suds to rise up within the interior of the cylindrical body and flow down the stand pipe. Means are provided to automatically capture and retain the float stem upon insertion thereof into the stand pipe.
Expired U.S. Pat. No. 3,894,555, the disclosure of which is expressly incorporated herein by reference, provides a similar float having a cylindrical main body and an outwardly and downwardly extending skirt. A terminal portion of the skirt extends downwardly beyond a terminal portion of the main body. During operation, the lower edge of the cylindrical main body is spaced a distance from the tub bottom, allowing suds to rise up within the interior of the main body and flow down the stand pipe. A float stem extends downwardly through a stand pipe and is operable to actuate a control switch to control a water inlet valve.
U.S. Pat. Nos. 4,256,136 and 4,301,829, the disclosures of which are expressly incorporated herein by reference, provide a float which is housed within a cover member at the bottom of the dishwasher tub. The float includes a pair of cylindrical walls which define concentric annular chambers. The inner annular chamber receives a stand pipe which, in turn, receives a float stem. The cover member retains and guides the float, and is provided with notched openings to enable water to pass into the interior of the cover member and move the float vertically. During operation, the lower edges of the cylindrical walls are spaced a distance from the tub bottom wall, allowing suds to rise up within the inner annular chamber and flow down the stand pipe.
U.S. Pat. No. 4,289,154, the disclosure of which is expressly incorporated herein by reference, discloses a self-cleaning float which has an open construction to allow food particles and the like to be rinsed from the interior of the float. The float includes a central shaft, an upper bowl-shaped member, and inner and outer concentric walls. The outer wall extends below the inner wall while the bowl-shaped member is directly attached to the shaft and overlies an open end of a stand pipe. Arms connect the bowl-shaped member to the inner and outer walls.
The prior art over-fill preventing floats suffer from the disadvantage that, when oversudsing occurs, as is common when hard water is used, suds may rise up within the float and flow down the stand pipe and onto the floor, giving the user the impression that there is a tub leak. Therefore, there exists a need in the art for a float which prevents or otherwise minimizes suds from reaching the stand pipe. There also exists a need in the art for such a float which includes means to prevent a vacuum from being created within the interior of the float which would cause the float to be adhered to the bottom of the tub.